Pile lifting device for use in sheet printing machines



Feb. 7, 1961 A. SCHWEBEL PILE LIFTING DEVICE FOR USE IN SHEET PRINTINGMACHINES 4 Sheets-Sheet 1 Filed April 30, 1958 A. SCHWEBEL Feb. 7, 1961PILE LIFTING DEVICE FOR USE IN SHEET PRINTING MACHINES 4 Sheets-Sheet 2Filed April 30, 1958 Feb. 7, 1961 A. SCHWEBEL 2,970,835

PILE LIFTING DEVICE FOR USE IN SHEET PRINTING MACHINES Filed April 30,1958 4 Sheets-Sheet 3 .DWEIHOF. H.001 F 62/! wean.

Br M M Hrromvevs Feb. 7, 1961 A. SCHWEBEL ,8 5

FILE LIFTING DEVICE FOR USE IN sum PRINTING MACHINES Filed April 50,1958 4 SheetsSheet 4 Inventor. #004 pic/ wean United States Patent PILELIFTING DEVICE FOR USE IN SHEET PRINTING 'MACHINES Adolf Schwebel,Olfenbach (Main), Germany, assignor to MABEG Maschinenbau G.m.b.H.,Ofienbach (Main), Germany Filed Apr. 30, 1958, Ser. No. 732,075 Claimspriority, application Germany Sept. 6, 1957 13 Claims. (Cl. 271-62) Thisinvention relates to machines for printing on sheets and has particularreference to the means therein for the uninterrupted feeding of thesheets into the printing mechanism and to the lifting of the piles ofsheets to enable such continuous feeding, and in which the piles arefirst raised by a main pile lifting device until nearly used up,whereupon the remaining rest pile is taken over at a certain height byan auxiliary lifting device which continues the lifting until a new pilehas been introduced. The invention is an improvement of the sheet liftershown and described in the specification of my Letters Patent of theUnited States No. 2,900,186,

- granted to me on an application filed on May 23, 1956.

In devices of this class it is usual to raise the combined main and restpiles of sheets first by a primary set of chains and to then continuethe lift on the rest pile by a secondary set of such chains. During theoperation of the secondary set of chains the main pile lifting means aregiven time to be lowered into their lowermost or initial position inorder to be loaded with a new pile, whereupon the operation justdescribed is repeated.

The known devices of this type suffer the disadvantage of requiringcostly and space consuming driving gears land controls which consist ofa great number of parts device in which these and other disadvantagesare absent, and which shall also be void of unnecessary complicationsbut be reliable in its function and easy to control and operate.

Another object of the invention rests in a generally simplifiedconstruction of the sheet lifting device enabling a reduction of partsand, therewith, of the costs of production and other associatedadvantages.

A further object of the invention is the provision of improvedelectrical means and connections to simplify the control andmanipulation of the main pile and rest pile lifting devices.

Other objects are the provision of adequate safety means to preventfaults in the transfer of the sheets from the piles to the sheet feedingmeans'and to safeguard the de vice against damage by inadvertance orother reasons, and to ensure the attainment of the exact end positionsof both the main and the auxiliary lifting devices in operation.

Still another object is the provision of means to safeguard the pilesexceeding their sheet feeding position, or to remain below the samerespectively, and to improve the pile lifting means and the means forcontrolli ng the same so as to enable the maintenance, at all 2,970,835Patented Feb. 7, 1961 feeding speeds, of the correct distance betweenthe top sheet of the main pile, or of the rest pile respectively, andthe sheet separating and feeding means.

These and other objects and improvements are obtained in accordance withthe invention by a sheet lifting device in which the pile of sheets isfirst raised by the main lifting device, in timed relation with thefeeding of the sheets into the printing mechanism until nearly used up,after which the remaining rest pile is taken over by an auxiliarylifting device having its own lifting means including a secondary set ofchains and an auxiliary lifting table in order to be lifted also invtimed relation with the feeding of the sheets into the printingmechanism. The auxiliary drive, controlled for example by the high speedwinding of an auxiliary lifting motor and comprising the aforesaidauxiliary lifting table with its pertaining lifting devices, raises therest pile step by step in accordance with the feeding of the sheets bymeans of a fine wire winding, whereupon the auxiliary lifting device isreturned into its starting position by the same auxiliary motor with itshigh speed winding.

If in a device of the said type a control disc is employed which, incooperation with a presser foot, or feeler, releases for each sheet acontrol stroke of a certain magnitude, and if the printing machine iscaused to run at an-increased speed with certain kinds of paper, thenthe disadvantage prevails, that the said control disc can not keep thecurrent to the driving means of the lifting device closed for asufiiciently long time, while it may remain closed for too long a timeif the machine is allowed to run at reduced speed, In these cases thepile will be lifted either too little or to much with the effect, thatit either does not reach the sheet feeding level or that it exceeds it.Both exigencies are most undesirable..

This is prevented, in accordance with the invention, in that the currentwhich may have accumulated in a condenser. is discharged into thedriving means of the auxiliary lifting device, or its ring windingrespectively, constantly and without regard to the sheet feeding speed,

as soon as the said feeler comes in contact with the decreasing heightof the pile. At this moment the switch, which is in connection with it,closes the current to the relay and to the switch, so that a contactordesignated up gets into action and raises the pile by another step inconformity with the feeding of the sheets into the printing mechanism.

In a modified form of the invention the swtich gears of the embodimentjust referred to are replaced by a considerably simpler arrangement,namely by the use of a lifting device in a plurality of electriccircuits, in which a transposition of parallel wires, or an electricswitch arm, is provided. In this arrangement one circuit raises the mainlifting device with its pile of sheets intermittently in accordance withthe feed of the sheets into the printing mechanism, while a secondcircuit causes the auxiliary lifting device to raise the rest pile alsoin conformity with the feeding of the sheets, and to return both liftingdevices into their starting positions.

The pile lifting devices in accordance with the invention can be furtherimproved in that the lifting means which continue the intermittentlifting of the rest pile can be moved at any desired height of thesteps. This is made possible by connecting a time relay, or atimeadjustable potentiometer, into the circuit, either before or afterthe condenser, so that by means of the timer the working circuits forthe drive of the lifting motors can be supplied to the condenser, or therelay, in conformity 0 with any desired height of the steps of the pilelifting trate the invention by way of example, several modifications ofthe device being shown. In these drawings:

Fig. 1 shows an embodiment of the pile lifting device in side elevation.

Fig. 2 is a plan view thereof.

Fig. 3 illustrates the auxiliary driving means.

Fig. 4 is a detail showing an electric control and safety device inconnection with the auxiliary pile table.

Fig. 5 shows a wiring diagram of the pile lifting devices.

Fig. 6 illustrates the arrangement of a condenser in a Wiring diagram asshown in Fig. 5.

Fig. 7 illustrates the wiring diagram of a more simplitied modificationof the pile lifting device.

Fig. 8 illustrates the arrangement, in the wiring diagram of Fig. 6, ofa potentiometer and time switch.

Fitted to the Walls 1 (broken off in Fig. 1) and 2 of the frame of asheet feeder for printing machines is the main pile lifting motor 3 withits intermittently operating switch gear, which is denoted by its maincomponents namely, the pawl 4, the pawl lifter '5, the ratchet Wheel 6,

gear wheels 7 and 8, worm 9, and the worm wheel 10. Keyed to the shaft11 of the worm Wheel are sprockets 12, over which and the sprockets 14,the main lifting chains 13 are passed. Supported on the carrier board 15is the main pile table 16, which may be a grate or the like, and whichcarries the main pile of sheets 12 so that it rests firmly against thefront stops 18. The sheet separating and feeding nozzles 19 of known orconvenient kind depend from the overhanging top of the frame to slightlyabove the top of the pile 17, while the sheet feeding roller 20 and thefeeding board 21 are arranged in front of the pile.

Denoted by the numerals 22 and 23 are the sprockets for the auxiliarylifting chains 24. They may be driven, for example, by a combined highspeed and fine wire motor 43, hereinafter called auxiliary motor, havinga high speed winding 44 and a fine wire winding 45 (Fig.

5). The endless driving chain 25 which runs over the motor drivensprocket 62 (Fig. 3) and the sprocket 63 is provided with abutments 26and 27 adapted to operate the switches 26a and 27a and to therebydisconnect the motor. The length of the chain 25 is such as will permitthe auxiliary lifting chain 24 approximately to pass through the liftingheight of the rest pile; the switches 26a and 27a thus representinglimit switches. A switch 28 (Figs. 1 and 5) is also provided to raiseand lower a ram 29 by means of which the upper position of the pile canbe determined. These parts constitute the main pile end switch, whichmeans, that when the pile 17 has reached a predetermined position inwhich it contacts with the ram 29, it moves the same upwards by acertain amount and actuates the lever 28 which disconmeets the maintable 16 and sets it at rest. This arrangement corresponds to the oneshown in Fig. 12 of my aforementioned U.S. patent specification No.2,900,186.

A lever 30 serves for the actuation of a switch 36 (Fig. 5) whichcomprises the switch block l with its contact bridges 31, 32, the switchblock II with its contact bridges 33, 34, and the switch block 111 withits bridge 35.

A push button 38 is provided to start the lifting motor 3 and to liftthe pile 17 by its supports 1'5, 16, while a push button 37 serves tolower the empty pile table into its starting position. These pushbuttons 37 and 38 also serve to actuate the auxiliary lifting motor 43for raising and lowering the auxiliary carrier bars 39, 40 including theauxiliary table, grate, or the like 41 which serves to support the restpile 42 and which has been slid in between the upper sheets shortlybefore the main pile 17 became used up. Another switch 46' serves forputting the continuous, uninterrupted lift of the pile into operation.

For maintaining the correct distance from the top surface of the pile tothe feeding nozzle 19, a presser foot or feeler 47 (Fig. 5) is provided,which may be of generally known type so that its precise configurationand function need not particularly be described. A cam 48 is provided tomove the feeler 47 over the pile and nder the edge of the top sheet 49after the same has been attracted and slightly lifted by the feedingnozzle 19. A Bowden cable 53 connects the feeler 47 to the lifter 5 ofthe pawl 4 and, over the said feeler, with the switch 51.

Associated with a one-way shaft 60 is a control cam 59 as shown on theright hand side of Fig. 5, which opens and closes a contact 61 of theauxiliary lifting device in timed relation to the feeding of the sheetsinto the printing mechanism of the printing machine. This arrangementensures the correct start of the lifting means for the rest pile 42,when simultaneously with the switch 60 also the switch 51 is closed bythe intermittent action of the feeler 4'7.

The carrier 39 of the auxiliary lifting device (Figs. 1 and 5) isprovided with an electric switch gear 52 comprising the contact bridges53 and 54. A connecting rail 55 extends over the whole width of thecarrier bar which, with its articulated lower part, is connected to theknob 56 of the switch gear 52 and also serves to limit the downwardmovement of the bar within the said connecting rail.

A hand crank 5'7 (Fig. 5) is provided which, when applied to the mainpile lifting motor 3, permits of adjusting the position of the pile asby raising or lowering the same by hand as may be required. By theapplication of the crank handle to its shaft a contact 58 is actuated,which disconnects the motor from the line and thus enables a safeactuation of the crank.

The mode of operation of the device just described is substantiallysimilar to the sheet feeder described in my former United States PatentNo. 2,900,186. After a pile of sheets 17 has been wheeled into thelifting device on a trolley or the like, the support 15 for the piletable 16 is suspended in the chain 13 of the lifting gear which isactuated by the motor 3. As a safety means against damage to the nozzle19, which is located directly above the pile 17, or the rest pile 42respectively, the lever 28 for the limitation of the pile end positionis turned into its operative position as shown in Fig. 5, in which theram 23 is approximately flush with the feeding means 20, 21 (Fig. 1). Bypressing the push button 38 the lifting motor 3 is started so as torotate the worm and worm wheel 9, 10 and to thereby move up the chain 13together with the pile table 15, 16 and the pile 17 resting thereon. Byturning the lever 30 the contact slide 36 (Fig. 5) of the combinedswitch blocks I, II and III becomes connected so that a circuit isclosed at 31, 32 (block I) and at 35 (block III) while block 11 is cutout by the opening of the contact bridges 33, 34.

Connected into ,the circuit which is closed over the contact bridges 31,32 (block I) are the contactors Ia (up and down), While the lead to theup contactor Illa is in a ready-for-work position by the contact bridge35 (block III) for an intermittent and fine control of the rest pile 42as by means of the motor 43 and its fine wire winding 45, when thecontinuous switch 46 is turned on. The contact bridges 33 and 34 of theswitch block 11, when open, interrupt the supply of current to thecontactor Ha (down and up) which, when closed, would raise and lower theauxiliary lifting means 39, 40 by winding up their chains through themotor 43 over its high speed winding 44 without any intermittentcontrol.

Simultaneously with the actuation of lever 30 as de scribed above, pawl4 has been lifted off the ratchet wheel 6 by means of the lifter 5.

Both switches 38 (up) and 37 (down) are now ready for the start of thepile lifting motor 3 without risk to any other devices or arrangements.When the button of the switch 38 is pushed in, motor 3 lifts pile 17 viathe contactor Ia (up) by means of the lifting chains 13 until its topsheet strikes the pile end limit switch, namely the ram 29, whereby thesupply of current is interrupted.

Now the lever 30 is turned back so that pawl 4 drops into the teeth ofthe ratchet wheel 6 and the contact bridges 31 and 32 are opened,whereby the switches 38 and 37 (up and down) are safeguarded againstunauthorized actuation, break or damage, by having become withoutcurrent. The feeler 47, which controls the position of the pile surfaceat every feed of a sheet into the printing mechanism by the nozzle 19,is now moved inwardly over the pile and lowered into contact therewith.The feeler 47 continues to descend as the distance between the nozzle 19and the top sheet of the pile becomes greater, so that the Bowden cable50, which is connected to the feeler 47, becomes actuated to cause therelease of pawl 4 by the lifter 5 to which the free end of the Bowdencable is attached. This, by any known or convenient means (not shown),causes an intermittent rotation of the ratchet wheel 6, whereby thechains 13 are moved over their sprockets 12, 14 and the pile 17 israised in timed relation to the withdrawal of the sheets as they are fedinto the printing mechanism of the machine.

After the pile 17 has been raised to approximately the level of thefeeding means and eventually worked off to a rest pile 42, an auxiliarypile table 41, which may be a grate or the like, is pushed in betweenthe pile table 16 and the rest of the pile 17 to right over the foremostcarrier bar 39 so as to rest on the two carriers 39 and 40. During thesemanipulations, which are known per se, the sheet lifting gear 4 to 12has suffered no interruption in its progressive pile lifting operation.

Now the continuous switch 46 is turned on and the push button 38 (up) isdepressed. This closes the circuit to the motor 43 over the bridge 33,34 (II) and the contactor Ila (up) with its high speed winding 44, sothat the carrier bars 39, 40 are raised by their chain 24 until arrestedbelow the auxiliary pile table 41, when the limit switch 52 (Figs. 4 and5) is opened through contact of the auxiliary table 41 with the carrier39, and the circuit A of the contactor IIa (up) closed at the bridge 54.Lever 30 must now be thrownin, which causes the switch blocks I and IIIto close and the block II to open so that pawl 4 becomes disconnectedand put out of operation. By now pressing push button 37 (down) the mainpile lifting motor 3 is reversed and the now empty pile table 16 loweredinto its initial position ready to receive another pile or to be wheeledout of the sheet feeding device.

The decreasing rest pile 42 is now intermittently lifted through meanssuch as the sprockets 62, 63 and the chains 24 driven by the fine wirewinding 45 of motor 43 in conformity with the feeding of the sheets intothe printing mechanism of the machine by the nozzle 19 as the feeler 47is caused to fall on the remaining pile by the action of cam 48, wherebythe switch 51, which is operated by the movement of the feeler, closesthe circuit through the fine wire winding of the motor. When the topsurface of the pile has eventually reobtained its correct position inrelation to the separating nozzle 19, the feeler 47 settles on the pilein so high a position as to be unable to close the switch 51, so thatthe fine wire winding of the motor and the contactor IIIa receive nocurrent and, therefore, can not come into action.

Meanwhile a new pile has been wheeled into the main lifting device ofthe sheet feeder and supported on the chains 13. Actuation now of thepush button 38 (up) causes the pile to be raised by the pile liftingmotor 3, until the top of the pile strikes against the lower side of theauxiliary table 41 and the end limit switch 52 as already described. andinterrupts the current in the lines A, B at the bridge 53 of the limitswitch 52 (Figs. 4 and 5).

Lever 30 is now returned and the contacts 31, 32 opened, whereby pawl 4becomes thrown into engagement with the teeth of the ratchet wheel 6.The auxiliary table has meanwhile been pulled out from the united piles17 and 42, the lifting of which is now performed, as in the beginning ofthe operation, by the separating means above the pile top surface andthe lifting gear 4 to 12 under the control of the feeler 47 taking itsposition on the top of the pile.

The contacts 33 and 34 remain closed, so that the carrier bars 39, 40 ofthe rest pile 42 can be lowered again by depressing the button 37 (down)through the high speed winding 44 of motor 43 for the reception of a newpile.

Both end positions of the auxiliary lifting device are ensured by theabutment 26 on the chain 25 actuating the corresponding switches 26a and27a (Fig. 3). This arrangement, however, can instead be provided on theelevator chain directly as shown in Fig. 5.

It is possible within the meaning of this invention to employsynchronized or polarized motors as auxiliary driving means for liftingand lowering, and for the inter- .mittent lifting of the auxiliarylifting means if this should be desired.

The wiring diagram which is shown in Fig. 6 corresponds substantiallywith the one shown in Fig. 5 but having a condenser 65, the rectifier 69pertaining thereto, a relay 67, 68, and the switch 66 which is mountedon the feeler 47.

During the operation of the device the condenser 65 takes up current inaccordance with its capacity. When the feeler 47 is lowered onto thepile after the same has diminished by the number of sheets already fedinto the printing device, the said feeler takes with it the switch 66which closes the circuit to the relay 67. Bridge 68 becomes attracted,and the current accumulated in the condenser sets the driving motor 43(Fig. 5) with its fine wire winding 45 and the contactor Illa (up) inmotion. The rest pile 42 with its carrier bars 39, 40 is raised inaccordance with the current which has been accumulated in the condenser,and is brought with its upper surface into its former position inrelation to the separating nozzle 19. The arrangement just referred tocauses the obtained level to remain constant without regard to theactual speed of the sheet feeding.

In the modified form of the invention as illustrated in Fig. 7, thelifting drive means are arranged in a plurality of circuits in which atransposition of parallel wires (switch) is arranged, one of whichserves to raise the main iiftingdevice together with its pile of sheets,and subsequently continues to lift it in conformity with the feeding ofthe sheets into the printing mechanism of the machine. A second drivemeans, including its auxiliary lifting devices, takes up the auxiliarypile table and continues to intermittently lift the rest pile, whileboth lifting drive means return the main and the auxiliary liftingdevices into their initial position. This takes place in the followingmanner:

Switch 36 is actuated by lever 30 whereby the bridges 31, 32 and 35 areclosed and the bridges 33 and 34 opened. The contact arm 73 is movedinto position A. If now the pile end switch or ram 29 is moved into aposition of readiness over the rest pile top by means of lever 28 asalready described with reference to the main pile, the circuit to thecontactor I (up) is closed when the push button 38 becomes depressed andthe high speed winding 71 of motor 70 receives current. The main liftingmeans 13, 15 (Fig. I) begin to lift the pile'17 until its top sheetcomes into the vicinity of the separating nozzle 19. Simultaneously withthis operation the pile end switch or ram 29 has become lifted off thetop surface of the pile and the circuit is again interrupted.

Now the continuation switch 46 is turned as indicated by the brokenlines, and the current flows over the closed bridge 35 into thecondenser 65 from which-in accordance with its capacity, when the feeler47 settles on a reduced pile and thereby closes the circuit to the relay67 and the bridge 68 with its switchit flows into the auxiliary motor70, or its fine wire winding 72 and the contactor Illa respectively,whereby the pile becomes lifted in conformity with the feed of thesheets into the printing mechanism.

Meanwhile the pile 17, owing tothe continuous with-v 7 i drawal ofsheets or the continuous lift respectively, has attained a heightapproximately in level with the feeding means 20, 21 so that theauxiliary table 41 can be pushed in between the pile table and the pile.i

Lever St is turned into the position shown in Fig. 7 so as to close thebridge 33 and 34. Current now flows to the auxiliary driving motor 43which, with its high speed winding 44 and the auxiliary carrying bars3?; 40, takes up the. pile on the auxiliary table 41. It comes to astandstill immediately when the switch 52 interrupts the circuit at thebar 39 (Fig. 4).

Then lever 30 is turned again so that the bridge 35 for the intermittentlifting of the rest pile 42 becomes closed after the electric switch arm73 has been changed over to B.

The fine wire winding 45 of the auxiliary lifting motor 43 receives thecurrent rationed to it and collected by the condenser 65 in accordancewith its capacitywhen the feeler 47 is lowered onto a fairly used-uppileand takes with it the switch 66 which is connected to it andeventually closes the circuit to the relay 67-which keeps the auxiliarydrive and its contactor Hlb in motion only as long as the originalworking position of the pile surface in relation to the separating means19 has been reattained.

Meanwhile, by the actuating of the push button 37 via the high speedwinding 71 of the lifting motor '70, the main lifting device has beenlowered via the contactor I (A, B) into its initial position.

As illustrated in Fig. 8, a potentiometer 90 of any known or convenientkind may be connected into the circuit either before or after thecondenser. It is provided with a time switch 91, which is so connectedto the potentiometer, that the pile, which diminishes by the constantwithdrawal of sheets, is so lifted in comparatively large or smallamountscorresponding to the thickness of the sheets-that the top surfaceof the pile remains in the activity region of the separating and feedingmean such as 19, and 21.

By this arrangement the condenser, or the relay respectively, 67receives the required capacity of working current which, when the feeler47 is not able to contact with 'the top surface of the pile, wouldsupply the lifting motor 'with current for the lifting of the pile up tothe desired height,

The arrangement just described can also be employed in such sheetfeeding devices in which the feeding of the sheets into the printingmechanism has to be interrupted every time a new pile is beingintroduced.

What I claim is:

1. In a sheet feeder for printing and the like machines having main pilelifting means including a first set of chains, a main pile table and,independent therefrom, auxiliary pile lifting means including a secondset of chains and an auxiliary pile table, for the continued lifting ofa rest pile from a lowermost position to a top position when the mainpile lifting means are being lowered for the receptionof a new pileof'sheets, and a feeler having electric contacts to regulate theposition of height of the pile as the same is lifted by the said mainpile lifting means, a main driving motor for driving said main pileliftng means, electric contacts for starting and stopping said motor, anauxiliary driving motor, a fine wire winding and a high speed winding insaid auxiliary driving motor for drivmg said auxiliary pile liftingmeans by said fine wire winding so as to lift said auxiliary tabletogether with the said rest pile thereon, means for intermittentlyadvancing said pile lifting means in timed relation to the feeding ofthe sheets into the printing machine, and contacts operable in the topposi- "tion of said auxiliary pile table for effecting the return Iofthe said auxiliary pile table into its lowermost position by the highspeed winding of said auxiliary motor.

2. In a sheet feeder for printing and the like machines -hav s. ma n p et ng e ns. n d a s s of chains, a main pile table, means to support saidmain pile table in said first set of chains, and auxiliary pile liftingmeans including a second set of chains and an auxiliary pile table forthe continued lifting of a rest pile from a lowermost position to anuppermost position when the main pile lifting means are being loweredfor the reception of a new pile of sheets, and a feeler having electriccontacts to regulate the position of height of said motor to becontrolled by the said contacts, a con- 'tinuous switch in said circuit,an auxiliary driving motor,

a fine wire winding and a high speed winding in said auxiliary motor forlifting said auxiliary pile lifting means by said fine wire winding,means for interrupting the circuit to the'sad high speed winding, amanually operable switch for closing the contacts of the said feeler andto the main lifting motor, a switch also in connection with the saidfeeler for intermittently driving said main lifting motor, mechanicalmeans in cooperation with the said switch for interrupting the supply ofcurrent to the line wire winding of said auxiliary motor in timedrelation to the working cycle of said auxiliary lifting device so thatthe rest p.le becomes lifted step by step in conformity with the feedingof the sheets into the printing machine when the said contnuous switchis closed.

3. A sheet feeder for printing and the like machines as set forth inclaim 2, in which is provided means for operating said continuous switchand for interrupting the auxiliary motor circuit, and means thereby toset the auxiliary lifting device at rest and to permit the main pile ofsheets to be lifted by the main pile lifting means only. 7

4. A sheet feeder for printing and the like machines as set forth inclaim 1 having carrier bars for the support of the auxiliary liftingtable, a set of chains for holding said carrier bars, a safety rail onat least one of said carrier bars, an electric switch gear in connectionwith said carrier bars, contacts in the said switch gear for initiatingthe raising and lowering of the auxiliary pile liftng means, an electricconnection between the said safety rail and the said switch gear, andmeans for voluntarily interrupting the uplift of the main pile and ofthe rest pile.

5. In a sheet feeder for'printing and the like machines as set forth inclaim 1, an auxiliary pile lifting device, a set of lifting chains onsaid auxiliary pile lifting device, carrier'bars suspended from saidlifting chains for the support of the auxliary lifting table, anelectric switch gear'on at least one of the said carrier bars, electriccontacts on the said switch gear for initiating the raising and loweringof said auxiliary pile lifting means, a safety rail on at least one ofthe said earner bars, an electric connection between the said safetyrail and said switch gear, and manually operable means for interruptingthe said connection at volunty.

6. In a sheet feeder for printing and the like machines having main'pile lifting means including a first set of lifting chains, a main piletable and, independent therefrom, auxiliary pile lifting means includinga second lifting chain, and an auxiliary pile lifting table for thecontinued lifting of a rest pile when the main pile lifting means arebeing lowered for the reception of a new pile, and a feeler havingelectric contacts to regulate the position of height of the pile, as itis lifted by the said main pile lifting means, carrier bars on thesecond set of lifting chains, a safety rail on at least one of the saidcarrier bars, spring means between said safety rail and said carrierbar, an electric switch gear on said safety rail, a contact bridgev forinitiating the uplift of the main pile, and means by which, on a newpile being lifted into engagement with a member of the auxiliary pilelifting means, the latter becomes lifted, while the said Switch on saidsafety rail and the circuit of the contact bridge for the uplift of themain pile are interrupted.

7. In a sheet feeder for printing and the like machines as set forth inclaim 6, the provision of electrically controlled means for correctingthe position of height of the auxiliary lifting means.

8. In a sheet feeder for printing and the like machines as set forth inclaim 6, means for limiting the high and low positions of the auxiliarypile lifting means, com prising, in combination with the auxiliarydriving motor, a driving chain intermediate the said auxIliary drivingmotor and said auxiliary pile lifting device, contact bridges on thesaid safety rail, a contact member on said driving chain, and switchesfor cooperation with said contact member for opening the contact bridgeson the said safety rail in order to interrupt the circuit to the saidsafety rail, or the lift of the auxiliary driving means respectively.

9. In a sheet feeder for printing and the like machines as set forth inclaim 6, means for limiting the high and low positions of the auxiliarypile lifting means, comprising, in combination with the auxiliarydriving motor, a contact member directly on one of the auxiliary liftingchains, and end switches for cooperation with said contact member forinterrupting the circuit between the said safety rail and the pilelifting device.

10. In a pile lifting device for pneumatic sheet feeders for use inprinting machines, means for feeding sheets from a pile into saidprinting machine, main lifting means including a driving motor, a pawland ratchet device for intermittently lifting said pile into contactwith said feeding means, a contactor, auxiliary lifting means forlifting a rest pile of sheets including an auxiliary driving motor foralso intermittently lifting said rest pile, and an electric feeler forcontinuously testing the height of the pile, a fine wire winding in saidauxiliary driving motor, a condenser in said fine Wire winding to supplycurrent in accordance with its capacity to the auxiliary lifting motoron the said feeler being lowered onto the rest pile of the sheets whenthe main pile has been reduced to a comparatively low height and formaintaining the electrical working energy constant and in propersequence of operation for the lifting of the rest pile when the saidfeeler contacts with the said pile, a relay in the feeler circuit, and aswitch in connection with the said feeler for disconnecting the supplyof current to said relay and the switch in the feeler circuit, so thatthe said contactor becomes actuated.

11. In a pile lifting device for use in printing and the like machinesas set forth in claim 10 having a main and an auxiliary pile liftingmotor, means for separating the top sheets from the pile at alwaysapproximately the same level, the main lifting motor also comprising ahigh speed winding for lowering the main pile table and for lifting apile of sheets up to the separating level, a fine wire winding for thecontinuous lifting of the combined main and auxiliary piles, said mainand auxiliary motors being arranged in separate circuits, a contactlever for connecting either the main or the auxiliary motor into thecircuit and to lift a rest pile only over the auxiliary lifting meansunder control of the fine wire winding when the said contact lever isconnected up to the circuit of the auxiliary lifting motor.

12. In a pile lifting device for use in printing machines as set forthin claim 10, a potentiometer for causing the lift of the pile step bystep in conformity with the feeding of sheets into the printing machine,and a time switch connected into the circuit in front of the saidcondenser by which the operating circuits for any desired height of pilelifting steps can be transmitted for the drive of the lifting motor tothe said condenser.

13. In a sheet pile lifting device for use in printing machines as setforth in claim 10, a potentiometer for causing the lift of a pile ofsheets step by step in conformity with the feeding of the sheets intothe printing machine, and a time switch connected into the circuit afterthe said condenser, by which the operating circuits for any desiredheight of pile lifting steps can be transmitted for the drive of thelifting motor to the relay in the potentiometer circuit.

References Cited in the file of this patent UNITED STATES PATENTS2,184,296 Goebel et a1 Dec. 26, 1939 2,658,752 Matteson Nov. 10, 19532,734,744 Backhouse Feb. 14, 1956 2,804,303 Henthorn Aug. 27, 19572,817,521 Koch Dec. 24, 1957

